Shearing head



Sept. 5, 1939. D. T Q'CONNOR 2,171,888

SHEARING HEAD Filed Feb. 25, 1938 ly-Z5 Patented Sept. 5, 1939 UNITEDSTATES PATENT. OFFICE 3 Claims.

My invention relates to improvements in shearing heads for electricallydriven hair clippers and dry shavers. More explicitly, the purpose ofthe invention is occupied with a clipper or razor of the dry shave type,providing for the removal of the toughest beard without injuring thetenderest skin, giving a superior shave because it is peculiarly suitedfor severing hair at its closest contact with the skin.

My invention purports the provisions of a clipper or shaver of this typeconsisting of a device, extremely simple in construction, of few parts,sturdy and exceptionally easy to use, efficient in operation, sanitaryand inexpensive to manufacture, applied without the use of shaving soapand utterly devoid of the slightest danger.

The invention may be grasped more readily from the following descriptionin conjunction with the accompanying drawing.

Figure l is an elevational view of an electric razor with my improvedcutter.

Figure 2 is a partial side elevation thereof.

Figure 3 is an enlarged partial cross section of the shearing head,taken approximately on the line 3-3 of Figure 1.

Figure 4 is an enlarged fragmentary sectional view of the cutting unittaken along line 4-4 of Figure 2.

Figure 5 is a partial, enlarged cross section of the cutter showing amodification of the tension device and the lubricating pad.

Figure 6 is an enlarged partial cross section and elevation of amodification embodying some of the principal improvements of the device.

Figure 7A is a greatly enlarged partial plane view of the slot detailsof the outside cutter.

Figure 7B is a greatly enlarged fragmentary plane view showing slotdetails before the outside cutter is formed.

Figure 7C is a greatly enlarged partial elevational view illustratingoutside cutter slot details.

Figure 8A is a greatly enlarged partial cross section of the insidecutter taken approximately on line 3--3 of Figure 1.

Figure 8B is an enlarged partial plane view of the inside cutter showingtooth details.

On the drawing, Figures 1 and 2 illustrate how the cutter is arranged inany suitable manner on a hollow handle or tool I00, in which is arrangedsome sort of motor IOI, which may be connected to an electric outlet bymeans of lead wires I02, extending from the bottom of the machine. .Aslot I03, in the top of the motor case I00, receives the bottom of theoutside cutter I04, which Is secured therein by a set screw I06,engaging the, corresponding i'nterlor screw I26, arranged on the case.

The outside cutter unit gle arm plate I08, a steel plate IIO, spotwelded to form a rigid outside element. The inside cutter III, is formedfrom a fiat piece so that its section, Figure 3, is approximatelyU-shaped.

In Figs. 3 and 4, the tension pad I I2, is a pliable 10 rubber stripwith a suitable clearance hole for the work arm II3 of the motor. Thework arm H3 passes through the clearance hole in the bottom of theoutside cutter insert, through the rubber pad opening and engages in anotch III, in the bottom of the inside cutter. This work arm I I3, moveswith a reciprocal or vibrating motion, moving the inside cutter III, toand fro while the outside cutter I0! remains stationary. Hair enters theoutside cutter slots Ill and as the ingo side cutter reciprocates iteffects the necessary shearing action between the edges of the insidecutter teeth H6 and the outside cutter teeth II5.

One of the principal difficulties encountered by the manufacturers ofshearing heads is in maintaining an even, constant, light tensionbetween the stationary and moving cutters. I have accomplished thisefiect by means of a novelshaped outside cutter arm plate I08 and atension pad H2, of rubber or a similar springy material. The uniqueoutside cutter arm is sturdy.

In assembling, the upper toothed side may be bent up or down slightlyinto approximately its proper position at which it is slightly flexible.The inside cutter III, is then inserted on the rubber pad which suppliesthe remaining necessary tension. The advances in the rubber industrymake possible the use of such a pad, pliant and resilient enough topermit the inside cutter III to make its reciprocating motion and alsoto 4 absorb any slight eccentricities in the shape or angles of eitherthe inside or outside cutter. There is no relative movement between thefaces of the rubber block and the faces of the cutter and the housing,the movement being obtained I01, consists of an aninsert I09, and a wall5 l by the internal movement of the rubber itself.

Another fault found in the shavers now on the market is the lack ofadequate lubricating facilities for the cutters. The lower section ofthe outside cutter I01, on my improved shearing head, formed by theoutside'cutter wall IIO, the angle arm plate I08, the angle arm platelugs I04, bent to fit securely around the outside cutter insert I 09,and spot-welded into a rigid unit, thus forms both a pocket orreceptacle for a 5 lubricating or tensioning device. The rubber tensionpad described above may be replaced by a similarly shaped absorbent feltpad, Fig. 5 III, which may be soaked in oil or other lubricant. Thispad, Ill, may be cut away at either end, as illustrated in the partialcross section Fig. 5, taken on approximately 4-4 of Fig. 2, to suitablyaccommodate a ball bearing H9, which will be lubricated indefinitely bythe oil-impregnated felt pad. Using a ball bearing will substantiallyreduce the total contact area between the cutters, hence reducingfriction and minimizing the load on the motor. Theyfelt, the balls orthe rubber may be used above 'or in any combination. when substitutingthe felt and balls, a lighter gauge metal, preferably non-corrosive, maybe present will cut hair,

more satisfactory, since a little more tension is required when therubber pad is not employed.

Many men object to dry shavers because they claim the dry shaver doesnot give a "close" shave and is too slow. Most dry shavers on sale at ifyou can coax it into the proper slots. This results in "slow and notvery "close shaving. My improved shearing head overcomes theseobjections by means of the novel shaped slots or teeth of the outsidecutter.

These slots, Figs. 7A, B and C, ill, are located along the top edge ofthe outside cutter and parallel to one another extending down over thecutting plane Fig. 3 ill, and ending short of the edge of the cutter, sothat the teeth are rigidly embodied in one piece, namely the ousidecutter.

angle arm plate Ill. It is to be noted that these teeth are bent at anangle over the tips of the inside cutter teeth Fig. 3, H6, and extendwell down past the plane of contact of the inside and outside teeth.Thus hair is readily admitted into the slots and the cutter ridessmoothly on the skin. Of prime importance is the shape of these slots.They are essentially in the shape of tear-drops, Fig. 713 Ill. The widerend of the slot admits the hair, the slot then narrows down toapproximately the thickness of a single hair at the root of the tooth.The slots at the roots of the teeth actually have an opening equal tothe thickness of a single hair.

The inside cutter, Fig. 8A, III, a section of which is generallyU-shaped and rigid with teeth formed by interdental spaces along atleast one lateral edge, has more teeth than the outside cutter. Thistends to keep the shearing head from clogging by permitting sheared hairto drop into the recess in the cutter immediately they are sheared andalso results in a faster, smoother-feeling shave.

A side wall of the inside and outside cutter has been omitted in thedesign, hence, this sheared of! hair which drops into the cutter isimmediately ejected from the recess which has three open sides.

Hence the cutter is clog-proof, a so far unattainable goal of thepresent day dry shaver manufacturers. The inside cutter teeth, Fig. 8AH6, when viewed laterally, unlike similar teeth which have a roundedbevel, taper to a sharp edge. Insidecutter teeth so shaped are extremelyimportant in this shaver as, in conjunction with the novel shaped andplaced slots in the outside cutter, they easily pick up hairs which maylie close to the skin as the shearing head is drawn across the skin,giving the user a fast, clean, close shave. This idea is contrary to thepresent belief of dry shaver manufacturers, most of whom assert that theoutside cutter does the combinll or picking up of close-lying hairs;however, in practice, I have found that the tapered or untapered toothdetermines to a considerable degree whether the cutter is slow or fast.An inside cutter may also be fashioned of a sumciently light gaugematerial non-corrosive or plated metal, so that when placed in theoutside cutter it will tend to spring open slightly, so exerting atension on the outside cutter.

Figure 6 shows a possible modification of my improved cutter embodyingseveral of its salient features.

One versed in the art may discern from the above description and drawingthat this cutter may be manufactured with comparatively few dies andoperations, that its assembly is simple, and hence it is economical tomanufacture.

It will be further seen that this improved cutter is easy to use, thecutting action being mainly against the grain of the hair. It cannotclog with hair due to the dispatch with which hair is ejected and itwill speedily cut cleanly and closely any type of hair.

Hence I claim as new and patentable:

1. A dry shaving unit consisting of a housing. a stationary toothedouter cutter secured to said housing, a reciprocating toothed innercutter mounted on said housing, and a pad of rubber interposed betweenthe housing and the lower face of the inner cutter so as to exertpressure on the upper face of the inner cutter against the inner facesof the cutter teeth of the outer stationary cutter.

2. In a device of the character described, a housing, a shearing headcomprising a stationary outer cutter secured to said housing and havingin cross-section substantially the form of a V lying on its side withthe upper arm of the V elongated and extending beyond the lower arm, aninner reciprocating cutter mounted on said housing and having incross-section substantially the form of a U lying on its side, the upperarm of said U having teeth in its extremity lying adjacent theundersides of said teeth of said outer cutter, said V-shape of saidouter cutter enhancing the resilient pressure of said'toothed endthereof against said toothed extremity of said inner cutter.

3. In a device of the character described, a housing, a shearing headcomprising a stationary outer cutter secured to said housing and havingin cross-section substantially the form of a V lying on its side withthe upper arm of the V elongated and extending beyond the lower arm, aninner reciprocating cutter mounted on said housing and having incross-section substantially the form of a U lying on its side, the upperarm of said U having teeth in its extremity lying adjacent theundersides of said teeth of said outer cutter, said V-shape of saidouter cutter enhancing the resilient pressure of the said toothed endthereof against said toothed extremity of said inner cutter, and a padof rubber interposed between the housing and the lower face of saidinner cutter so as to exert pressure on said toothed extremity of saidinner cutter against said toothed end of said outer cutter.

DONALD T. O'CONNOR.

